1. Field of the Invention
The present invention relates to a micro-electronic component for a passive card without contact, a passive card without contact carrying such a component, a station intended to be electromagnetically coupled to such a passive card without contact and a production process for the micro-electronic component.
The present invention has general application in the uni- or bi-directional transfer of data between a passive card without contact and a remote station.
2. Description of the Related Art
In general, a card without contact either contains or does not contain an internal energy source. In the first case, it is an active card, whereas in the second case it is a passive card.
A passive card without contact either receives the energy it requires by electromagnetic coupling from the remote station. It is known as a proximity card if its operating distance from the station is generally less than or equal to a few millimeters.
In practice, a passive card without contact carries a micro-electronic component comprising a coil (also known as an antenna or self-inductor) for supplying power to the component by induction and for inductive transfer with the station of a signal representing data, and processing means supplied by the coil and able to process the signal thus transferred or to be transferred.
From a technological point of view, there are two separate categories of passive cards without contact.
In the first category, the electromagnetic coupling is provided by an antenna (or several), formed on a substrate different from that of the micro-electronic component. More precisely, the antenna is engraved on a selected substrate itself placed in the constituent material of the card (PVC, ABS, polycarbonate etc). The micro-electronic component is itself attached to the antenna by soldered wires. This first category is referred to below as a passive card without contact with assembled coil. The production process for this card is complex because of the operations required for assembly by wire.
In the second category, the coil is engraved directly on the micro-electronic component, usually a silicon material. This second category is referred to below as a passive card without contact with integral coil, or “coil on chip”. The production process for this integral card is considerably simplified in relation to that of the assembled card as various assembly operations are omitted, in particular connection of the micro-electric component to the antenna.
However, the surface of an integral coil is generally smaller than that of an assembled antenna in so far as the surface of the integral coil is limited by the surface of the component, which is preferably as small as possible to reduce production costs, and by the area necessarily occupied by the processing means of the component, which limits the energy transmitted to the passive card without contact.
Also the three-dimensional configuration of the conductive turns of an integral coil brings about a number of difficulties, in particular the creation of parasitic components, for example, the formation of a capacitor, the capacitance of which may be not insignificant, which leads to a reduction in the electrical power available on said component.
The article ELECTRONIQUE No. 25, February 1993, PARIS, pages 49-51 XP 00334566, MOUGAHED DARWISH, “Choisir sa technologie pour un asic mixte”, describes an integrated circuit without an internal power supply comprising processing means for processing a signal representative of data to be transferred to a remote station, and an integral coil on silicon in order to supply the energy to the integrated circuit.
Only a small number of windings is made here using a conventional metallisation process for integrated circuits which prevents induction of sufficient energy to supply the processing means ensuring a bidirectional transfer of data.